Memory effects in complex materials and nanoscale systems

Memory effects are ubiquitous in nature and are particularly relevant at the nanoscale where the dynamical properties of electrons and ions strongly depend on the history of the system, at least within certain time scales. We review here the memory properties of various materials and systems which appear most strikingly in their non-trivial time-dependent resistive, capacitative and inductive characteristics. We describe these characteristics within the framework of memristors, memcapacitors and meminductors, namely memory circuit elements whose properties depend on the history and state of the system. We examine basic issues related to such systems and critically report on both theoretical and experimental progress in understanding their functionalities. We also discuss possible applications of memory effects in various areas of science and technology ranging from digital to analog electronics, biologically-inspired circuits, and learning. We finally discuss future research opportunities in the field.Comment: Review submitted to Advances in Physic

Memory effects in response functions of driven vortex matter

Vortex flow in driven type II superconductors shows strong memory and history dependent effects. Here, we study a schematic microscopic model of driven vortices to propose a scenario for a broad set of these kind of phenomena ranging from ``rejuvenation'' and ``stiffening'' of the system response, to ``memory'' and ``irreversibility'' in I-V characteristics

Memory functions and Correlations in Additive Binary Markov Chains

A theory of additive Markov chains with long-range memory, proposed earlier in Phys. Rev. E 68, 06117 (2003), is developed and used to describe statistical properties of long-range correlated systems. The convenient characteristics of such systems, a memory function, and its relation to the correlation properties of the systems are examined. Various methods for finding the memory function via the correlation function are proposed. The inverse problem (calculation of the correlation function by means of the prescribed memory function) is also solved. This is demonstrated for the analytically solvable model of the system with a step-wise memory function.Comment: 11 pages, 5 figure

Performance Implications of NoCs on 3D-Stacked Memories: Insights from the Hybrid Memory Cube

Memories that exploit three-dimensional (3D)-stacking technology, which integrate memory and logic dies in a single stack, are becoming popular. These memories, such as Hybrid Memory Cube (HMC), utilize a network-on-chip (NoC) design for connecting their internal structural organizations. This novel usage of NoC, in addition to aiding processing-in-memory capabilities, enables numerous benefits such as high bandwidth and memory-level parallelism. However, the implications of NoCs on the characteristics of 3D-stacked memories in terms of memory access latency and bandwidth have not been fully explored. This paper addresses this knowledge gap by (i) characterizing an HMC prototype on the AC-510 accelerator board and revealing its access latency behaviors, and (ii) by investigating the implications of such behaviors on system and software designs

Manganese bismuth thin film for large capacity digital memories

Material and system research defines accurate memory characteristics in regard to write, read, erase and data operations of manganese bismuth materials

The Spatial Memory of African Elephants (\u3cem\u3eLoxodonta africana\u3c/em\u3e): Durability, Interference, and Response Biases

Women and elephants never forget an injury. -Saki (H. H. Munro), Reginald on besetting sins, in Reginald (1904) I am not sure whether the satirist H. H. Munro believed Saki\u27s claim, although it may well be true (at least with regard to elephants). This chapter will examine some characteristics of elephant memory more systematically than did Saki. In general, it is to an animal\u27s advantage to remember some aspects (usually the stable features) of a situation for long periods and to remember other aspects (usually the unstable features) only temporarily. Consistent with recent arguments questioning the value of cognitive constructs for studying animal behavior (Grau 2002; Staddon 2001a,b; Wright and Watkins 1987), I will use reference memory and working memory (Baddeley and Hitch 1974; Honig 1978) only as descriptive terms indicating formal task requirements. (See Olton, Becker, and Handelmann 1979.) The stable characteristics of the test situation (such as the shape of the spatial array of food sources) are said to involve reference memory; those features that vary across trials (such as the sequence of food sites visited on a trial) are said to involve working memory. My main goal is to demonstrate that elephants can remember which locations they have visited during a spatial memory test similar to the radial maze (Olton and Samuelson 1976). The data will show that elephants rely on memory to solve several spatial problems, rather than relying on their response biases (Dale and Innis 1986) or their excellent olfactory abilities (Rasmussen and Krishnamurthy 2000). In addition, I will describe research showing that performance on the memory task is susceptible to proactive interference and that the retention of reference memory components of the test procedures is durable

Electro-Mechanical Simulation of Switching Characteristics for Nanoelectromechanical Memory

The static switching properties and readout characteristics of proposed high-speed and nonvolatile nanoelectromechanical (NEM) memory devices are investigated By conducting a three-dimensional finite element mechanical simulation combined with an electrostatic analysis, we analyze the electromechanical switching operation of a mechanically bistable NEM floating gate by applying gate voltage. We show that switching voltage can be reduced to less than 10V by reducing the zero-bias displacement of the floating gate and optimizing the cavity structure to improve mechanical symmetry. We also analyze the electrical readout property of the NEM memory devices by combining the electromechanical simulation with a drift-diffusion analysis We demonstrate that the mechanically bistable states of the floating gate can be detected via the changes in drain current with an ON/OFF current ratio of about 3 x 10 (C) 2009 The Japan Society of Applied Physic